Want mother out of nursing home

My 86 yr old mother went in to what I call a "funk" last January.
My step father and I decided he could no longer take care of her, so we found an empty bed at the local VA Nursing Home.
My mother has worked very hard to improve her health and is now able to think for herself and is completely ambulatory.
My step father has always been VERY controlling and wants to continue to "call the shots"
My sister and I have talked to him, telling him we would like her to come home and receive home health care.
Today while visting her in the nursing home, he came in to the room. She practically got down on her hands and knees and begged him to take her out of there! He told her she needed to get better before he could take care of her. Before he came in to the room I had a conversation with the nurse and asked her how she thought my mother was doing. She stated she is doing much better than she was when she came in. I agree. She needs hardly any care and is in better shape than 90% of the people that are in there. I explained that to my step father and he became very agitated! Agitated to the point we almost physically got in to an altercation.
My mom has stated she would divorce him if he isn't willing to get her out of there.
I told him, I would let her come and stay with me and they could pay for the home health care while I was at work. He told me I would not do this and HE would not pay for it with HIS money! I explained to him, my mom would pay for it with HER money! That just made him more upset. He is VERY hot headed and has always been that way.
My question is: what are my rights and her rights? She is of sound mind and body to make her own decisions. Would she need to divorce him to access THEIR money?
Right now, his daughter is taking care of their finances which really makes me nervous. For all I know, they are hiding this money in fear of my mom using it all up in the nursing home.